Scientists cracked fluid math by studying black holes
A 20-year rebuild found that flow equations come from deep symmetries, and point to behaviors the old math missed.
Quanta Magazine · Theory of Fluids Enters the 21st CenturyThe math that describes water and air got a major upgrade with help from black hole physics.
A quantum soup is an extremely hot and dense state of matter that flows like a nearly perfect fluid. Through a theoretical link called holography, the equations for such a soup match the equations for a black hole in a higher-dimensional space, so a difficult flow problem can be recalculated as a more tractable gravity problem.
After two decades of work, physicists used those clues to rebuild flow theory around fundamental properties called symmetries. The rebuild gives the 19th-century Navier-Stokes rules a deeper foundation and lets scientists move past them. The revised picture predicts additional flow effects caused by the motion of microscopic particles.
Insights from black holes and cosmology thus helped update a theory of everyday life.
Questions people ask
What is a quantum soup?
It is an extremely hot, dense state of matter where particles lose their separate identities and flow together. Physicists create tiny amounts briefly by colliding heavy atomic nuclei at near light speed. The resulting droplet flows like a nearly perfect fluid.
What does a black hole have to do with a fluid?
Through a theoretical link called holography, the math for certain hot quantum fluids matches the math for black holes in a higher-dimensional space. A calculation that is hard on the fluid side can become easier on the gravity side. Physicists used that correspondence to gain insight into fluid behavior.
What are symmetries in physics?
A symmetry is a change that does not matter to the outcome. A circle, for example, looks the same after rotation by any angle. In physics, such invariances sharply limit which equations are allowed, so they can reveal the rules a fluid must obey.